Effect of Cushion Layers on Mechanical Characteristics of Spiral Case Structure in Hydropower Station

Abstract

The effects of deformation modulus, thickness and range of cushion layer on mechanical characteristics of spiral case in hydropower station has been analyzed using the finite element program ANSYS and nonlinear contact theory. The result shows that when cushion layer scope and poisson ratio is fixed, as the elastic modulus of cushion layer decreases, the deformation and stress of spiral case increases, surrounding concrete load-bearing ratio of water pressure reduces. If the cushion layer deformation modulus is fixed and the range of cushion layer extends to 10 degree site bellow the waist of spiral case, the steel spiral case stress decrease, the radial stress transferred from the spiral case to surrounding concrete increase by about from 0.01MPa to 0.03MPa, and load-bearing ratio of concrete increase, when the cushion layer Poisson ratio increases from 0.25 to 0.35.